I have said it before, and I will try not to bang on about it too often, but cosmos are not just wonderful, they are essential.
Last night I was invited to a garden to give some advice and, before it got so dark that I was almost feeling my way around (the nights are really drawing in) I had a chance to sort out a few problems. Despite being so late in the season there was still some colour, primarily from some healthy roses that were evidence of some careful cultivation. But the stars of the garden were definitely the cosmos. These had been grown from seed by the owner and this is definitely the right thing to do. This is because, in garden centres, you are only likely to find shorter kinds. The reason is simple – cosmos grow so quickly that the taller kinds take up too much room and get too big on the benches and they also flower later and no one would buy a tall cosmos without flowers when there are small ones with large flowers on next to them.
But then you would be missing out. Good though the small ones are, they ‘burn out’ too quickly while the taller ones keep going into autumn.
Now there is a problem, of course. As I have mentioned before, some of the cheap mixes of tall cosmos contain a lot of plants that do not flower until frosts are ready to strike.
So you need to choose named, tall cosmos (we are talking about C. bipinnatus by the way). I am not a great fan of the doubles and both the ‘Double Click’ and ‘Bonbon’ colours are mildly disappointing, I think because I love the simplicity of the singles. But I wouldn’t put you off trying them. Choosing just one is impossible but I love the rich red of ‘Rubenza’ (also called ‘Rubinato’ for some reason) which has a smoky hue and is best lit from behind, and I like the pink-eyed, white ‘Sweet Dreams’. Oddly, I also like the rather fussy ‘Fizzy’ series with extra, narrow ‘petals’ in the centre. All these can be bought from Plants of Distinction in Europe (they have more than 20) but also from other seed companies.
Cosmos are easy from seed – if you have never sown seeds before then start with cosmos. The seeds are large and easy to handle. Just don’t sow too early, they grow fast and usually germinate in less than a week. Sowing in April is usually early enough.